The present invention concerns a mixing tool for attachment within a drum the mixing arm of which is mounted to a rotatably borne shaft and whose mixing body, mounted on the mixing arm is directed towards the inner surface of the drum.
A mixing tool of this type has become known in the art e.g. through DE 43 44 995 A1.
Mixing tools have been known in the art for decades and are used in substantially horizontally directed drums to mix bulk products and liquids of all kinds. The mixing tools are thereby mounted to a shaft which is rotatably borne in the drum. In order to achieve as complete a mixing of the bulk products as possible, the mixing tools should penetrate in particular through the bulk product whirling at the inner surface of the drum. Towards this end, the mixing tools are disposed within the drum in such a fashion that the separation of the mixing tools with respect to the inner surface of the drum is small. Due to expansion of the material (of the drum and/or of the mixing tool) or due to the intrinsic weight of the mixing tool, the separation between the mixing tool and the inner surface of the drum can decrease. A safety margin is therefore always required between the mixing tool and the inner surface of the drum.
When mixing particular products, a fraction of the bulk product can become attached to the surface of the drum in the region between the mixing tool and the inner surface of the drum. In particular, bulk products having sticky and hardening components tend to produce this type of product deposit. This sticky and hardened portion of the processed product interferes with the operation of the mixing tools. The tools can then undergo wear even after short operation times and/or the quality of the product being processed is compromised.
For this reason, prior art has already used so-called "cleat blades" as, e.g. known in the art from the brochure "Industrial Mixing in Continuously Operating Lodige-Mixers" from the company Lodige, published in 1993. These cleat blades attempt to positively influence the properties of the product deposit formed. The product deposit on the inner surface of the drum is broken-up by the cleat portion of the mixing tool during mixing. If, however, the mixing product has components which harden relatively quickly and which can form a hard product deposit, the action of such a cleat blade is insufficient to completely suppress formation of a product deposit on the inner surface of the drum.
In order to avoid this problem, prior art has already proposed introducing two cleat profiled mixing tools on one mixing arm. The overlapping of two cleat profiles allows for better processing of the product deposit. However, the mixing arm is subject to substantial load during the mixing process due to the presence of two mixing bodies having cleated sections. In addition, the inner volume of the drum available for accepting bulk product is disadvantageously reduced.
The technical problem underlying the present invention is therefore to develop a simply constructed mixing tool through the use of which nearly all bulk products or product masses which tend to produce product deposit can be processed without having material deposition occur in the region between the inner surface of the drum and the mixing body.